1. Field of the Invention
The present invention relates to a time switch whereby on and off conditions of internally installed contact points control the operation of an electrical load according to a desired time schedule.
2. Description of Background Information
A conventional time switch, such as the type described in Japanese Kokai (laid open) Patent S63-29427, includes a modular structure assembled from a motor that rotates at a uniform speed, a ratchet gear driven by a gearwheel transmission powered by the motor, and a first gear that meshes with the ratchet gear. The time switch also includes a sub-dial that rotates clockwise at a rate of one revolution per hour relative to the rotation of the ratchet gear, a gear that meshes with a second gear attached to the rotating shaft of the sub-dial, a dial that rotates clockwise once during a twenty four hour period relative to the rotation of the sub-dial, a scheduling clip with a finger that projects from the circumference of a dial used to set a desired operating time schedule, and an internal contact point activating mechanism that opens and closes the contact points through contact with a contact element that is freely settable to a desired time. In the time switch of Japanese Kokai (laid open) Patent S63-29427, the ratchet gear, which is rotatably driven by motor torque supplied through the gearwheel transmission, rotatably drives the sub-dial through the sub-dial shaft. Although the dial is rotationally driven by meshing with the second gear on the sub-dial shaft, the sub-dial shaft rotates only in one direction due to the ratchet mechanism formed by the first gear and ratchet gear at the rotating sub-dial shaft. As a result, even though the sub-dial can be turned manually to set the time, it can only be turned in one direction, thereby making it time-consuming to set the time. For example, when changing the time schedule due to the enactment of daylight savings time, it would be easy to turn the sub-dial back one hour from a current setting of seven o'clock to a six o'clock setting. Because the sub-dial can only be turned in the clockwise direction, however, it must be advanced twenty three hours to effect the desired time change. As a result, changing the time becomes a time-consuming operation. Additionally, in the time switch described in JP 63-29427, a knob is provided to manually turn the rotating shaft to one of three positions which include (1) a position at which the contact points are turned “on and off” in response to the scheduling clips, (2) a position at which the contact points are turned “on” regardless of the scheduling clips, and (3) a position at which the contact points are turned “off” regardless of the scheduling clips.
Moreover, with this type of conventional time switch, there are times when there is no direct relationship between the scheduling clip and the position of the contact points directly after the dial has been manually turned.